In the neurological assessment of an unconscious patient, pupil response is known to be a vital aspect of the diagnostic process. Regular assessment of the size, reactivity to light and equality of pupils is essential for early recognition of neurological deterioration in situations where intra-cranial pathology is a threat. As such this assessment is regularly carried out in paramedic, intensive and high dependency care situations.
The current method of practice is to manually measure these aspects using a bright light, which stimulates reactivity of the pupil and make a note of the dilation compared to the original size of the pupil Actual measurements taken are then compared with a card having different pupil sizes mated thereon. This method of assessment is time consuming, and subjective.
Pupilometers have been developed for use in the assessment of eye shape and condition, monitoring tiredness, and in the detection of drugs or alcohol in a person.
A hand-held pupilometer is described in U.S. Pat. No. 6,022,109 Dal Sante). This pupilometer detects and measures pupil diameter and pupil response to a light stimulus. Also described is software to permit the diagnosis of alcohol or drug presence. However, use of this pupilometer requires the active participation of the user.
Another hand-held pupilometer is described in U.S. Pat. No. 6,199,985 (Anderson). This patent describes a method for measuring optical power output from the pupil. However, the pupilometer described in the patent requires complex optometric components.
Another hand-held pupilometer is described in U.S. Pat. No. 6,260,968 (Stark). The device described includes an LCD display via which prompts to the operator are given. The pupilometer described in this patent uses a “flying spot” algorithm to establish a circumference fitting the pupil, and the pupil radius. The pupilometer includes software to aid diagnosis. Again, the pupilometer described in this patent requires complex optometric components.
It would therefore be desirable to provide an improved pupilometer.